This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol1", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
Of all the medicines in common use, only the products of the genus Strychnos belong properly to this class. Some others have a stimulant influence over the spinal functions, but they have also properties which class them elsewhere, and there is no one which approaches in power those here referred to. The products of the two species, Strychnos Nux vomica and S. lgnatia, are so similar, I might say identical in character, that it is scarcely advisable to consider them distinctly. They are, therefore, united in the following article.